^^^ 6 ft, 170 doesn't sound like a 14.5 inch neck to me. I would measure again before I bought a shirt which I couldn't try on before purchase.
Buy an Extra Slim Fit or Slim Fit Brooks Brothers OCBD (oxford cloth button down) on B&S. They can be had for $45 each. IMO the made in USA BB OCBD is the most versatile shirt out there.
Unfortunately it is correct, I'm wearing a 15" ted baker shirt currently, it hasn't been through a wash cycle yet and I can comfortably put two finger under the collar with room to spare.
Find a way to exercise your neck. Seriously. There is no OTR I can think of that's going to make a size that fits you. I'm a little taller than you, and about 15 lbs lighter, with a neck that's two inches larger and even I have trouble finding shirts that fit.
BTW how is TM Lewin, I keep seeing them and thinking cheeeeeep but if they're crap I don't wanna buy them.
I think as I may have mentioned to you in a couple of posts on the MC Casual thread, I am trying to bulk up my upper body, particularly my shoulders that were thought to be too narrow. Maybe that will lead to my collar size increasing. I think I'll just have to put off dressing well for a few more months and have to accept dressing average for now.
As for quality of TM Lewin, I haven't bought from them before so I can't say though at 5 shirts for £100 they seemed the right price. Unfortunately I was unsure if I wanted 5 dress shirts and the fit wasn't quite right so I passed them up.